/*
 * Copyright (c) 2009, University of Bristol
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2) Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3) Neither the name of the University of Bristol nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */
package org.wf.arnos.logger;

import java.lang.reflect.Field;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.util.ReflectionUtils;

import static org.springframework.util.ReflectionUtils.FieldCallback;

/**
 * Before each bean gets initialized (right after it gets constructed), this
 * bean will iterate over the fields of the bean to detect any @Logger
 * annotations and construct and inject a new logger instance.
 * See: http://www.tzavellas.com/techblog/2007/03/31/implementing-seam-style-logger-injection-with-spring/
 * @author Chris Bailey (c.bailey@bristol.ac.uk)
 */
public class LoggerPostProcessor implements BeanPostProcessor
{
    public Object postProcessAfterInitialization(final Object bean, final String beanName) throws BeansException
    {
        return bean;
    }

    public Object postProcessBeforeInitialization(final Object bean, final String beanName) throws BeansException
    {
        ReflectionUtils.doWithFields(bean.getClass(), new FieldCallback()
        {
            public void doWith(final Field field) throws IllegalArgumentException, IllegalAccessException
            {
                if (field.getAnnotation(Logger.class) != null) {
                    Log log = LogFactory.getLog(bean.getClass());
                    ReflectionUtils.makeAccessible(field);
                    field.set(bean, log);
                }
            }
        });
        return bean;
    }
}
